1. Field of the Invention
This invention relates to photography and to novel chemical compounds useful therein. More particularly, it relates to novel chemical compounds useful in the development of photosensitive silver halide materials and to photographic products, processes and compositions employing the same.
2. Description of the Prior Art
In recent years, there has been a growing interest in heterocyclic developing agents, i.e., developers containing a heterocyclic ring as part of their structure. Some of these developing agents have the conventional hydroxyl or amino developing groups substituted on adjacent carbon atoms of a heterocyclic ring to provide structures similar to those of the developing agents in the aliphatic and aromatic series. Still other heterocyclic developing agents, as exemplified by 1-phenyl-3-pyrazolidinimine and 1-phenyl-3-pyrazolidone (commercially available under the trademark "Phenidone") have one of the functional developing groups included as part of the heterocyclic ring. 1-phenyl-3-pyrazolidinimine forms the subject matter of British patent specification No. 757,840 and 1-phenyl-3-pyrazolidone and its 4,4-dialkyl derivatives form the subject matter of U.S. Pat. Nos. 2,289,367 and 2,772,282, respectively. Though these developing agents are useful by themselves, their commercial significance resides primarily in their ability to form superadditive mixtures with other developing agents, for example, hydroquinones.
The present invention is concerned with novel heterocyclic compounds comprising a new class of silver halide developing agents useful in conventional and in diffusion transfer photography, both black-and-white and color.